Thermoelectric properties of La-doped A-site SrTiO 3 ceramics synthesised by the sol-gel auto-combustion technique

Sr(1–x)LaxTiO3 (SLTO) nanopowder (x = 0, 0.01, 0.05, 0.07, and 0.10) were effectively synthesised by the sol-gel auto-combustion process. Bulk ceramics samples were produced by spark plasma sintering (SPS) in an Ar atmosphere. The XRD pattern of the undoped SLTO nanopowder showed the pure phase and the impurity phase (TiO2) was detected in the La-doped SLTO samples. However, the impurity phase disappeared after producing the bulk samples with the SPS process. All the samples exhibited a negative Seebeck coefficient (S). The electrical conductivity (σ) and negative Sof all the SLTO samples increased with increasing temperature and reached a maximum value at 800 K. The thermal conductivity (κ) decreased with increasing temperature and increasing La content. The SLTO with x = 0.01 showed the largest σ, negative S, power factor (S2σ) and dimensionless figure of merit (ZT) at 800 K.